While watching a passing 767 approaching Seatac, observed a brilliant silver dot/orb in the sky to the northeast, at about 60 degrees elevation. This was not a weather balloon, cloud, rocket, bird, or other explanable phenomenon. It did not flicker, or appear to move, there was no apparent motion, trajectory, or drift. It hovered for about 5 min. Another observer independently verified what I saw. A similar object with a distinct greenish tint appeared from the right (east) and approached the original silver one, on an intersecting course, and then narrowly avoided it, and proceeded to turn "around" it in a clockwise arc. I cannot estimate the size or distance, but comparison with passing aircraft indicated that this was VERY high. After about 10 min it faded away.